The present invention relates generally to wireless vehicle tire pressure monitoring and, more particularly, to a system and method for wireless vehicle tire pressure monitoring that includes automatic recognition of tire location.
It is known in the automotive industry to provide for wireless monitoring of vehicle tire parameters, particularly tire pressure. In such tire pressure monitoring systems, tire pressure sensors and radio frequency (RF) transmitters are mounted inside each tire, typically adjacent the inflation valve stem. In each tire, the tire pressure sensed by the tire pressure sensor is transmitted by the transmitter to a receiver located on-board the vehicle. The tire pressure information delivered to the receiver by the RF signals from the transmitters is subsequently conveyed to a vehicle operator or occupant, typically in the form of a display.
Exemplary tire pressure monitoring systems are described and shown in U.S. Pat. Nos. 6,112,587 and 6,034,597. Conventional tire pressure monitoring systems, however, are not capable of automatically recognizing the particular tire location (e.g., front left (FL), front right (FR), rear left (RL), rear right (RR)) associated with an RF signal received from a tire transmitter without the use of additional equipment or devices. That is, in conventional tire pressure monitoring systems, in order to provide a vehicle operator with information specific to each vehicle tire, an initialization or sign-up operation must be undertaken by a technician or vehicle owner to program the system so that each RF signal from a tire transmitter will be associated with a particular tire location.
Such operation, however, can create problems when tires are subsequently rotated or changed from their initial locations to new locations. Each time the vehicle tires are rotated, initialization or sign-up must be repeated to ensure that the system continues to operate properly by conveying accurate information, including tire location, to the vehicle operator. This initialization requirement makes tire rotation more complex, and increases the possibility of inaccurate operation of the system. These problems can be overcome through the use of additional equipment or devices, as previously mentioned, for use in determining tire locations. For example, multiple antenna, each associated with a particular tire, and/or specialized transmitters may be employed. Such additional equipment or devices, however, can add significant cost to a tire pressure monitoring system.
Thus, there exists a need for a smart or adaptive tire pressure monitoring system and method that automatically recognizes tire location even after tire rotation, without the need for subsequent initialization or sign-up operations, or additional equipment or devices. In that regard, the amplitude and pattern of an RF tire pressure signal transmitted from a rotating tire typically vary during transmission. Such a smart tire pressure monitoring system and method would use signal amplitude over time from RF tire transmitters as a signature for each tire location. Such a system and method would preferably include a receiver optimally located on the vehicle, as well as a microcontroller or digital signal processor (DSP) for collecting amplitude versus time data from each tire transmitter and processing such data using pattern recognition techniques to determine the tire location from where the data was transmitted. Advantageously, tire pressure sensor identification codes and such a location signature could be combined to provide the vehicle operator with tire location information.
Accordingly, the present invention provides an improved vehicle tire pressure monitoring system and method. More particularly, the present invention provides, in a vehicle having a plurality of tires, each tire having a tire location associated therewith, a system for monitoring tire pressure. The system comprises a plurality of tire pressure monitors, each monitor for mounting in one of the plurality of tires, each monitor comprising means for determining tire pressure and a transmitter for transmitting a tire pressure signal representative of the tire pressure determined. The system further comprises a receiver for mounting on board the vehicle for receiving the tire pressure signals, the receiver comprising an antenna to be located on the vehicle at a site, wherein each tire pressure signal has an amplitude and, for each tire location, the amplitude has a unique pattern over time for the antenna site. The system still further comprises a controller for mounting on board the vehicle, the controller to be provided in communication with the receiver for collecting and processing the tire pressure signals to automatically identify the tire locations associated therewith based on the unique amplitude patterns, the controller further for generating control signals for use in conveying tire pressure and location information to a vehicle occupant
According to the present invention, a method is also provided for monitoring tire pressure in a vehicle having a plurality of tires, each tire having a tire location associated therewith. The method comprises providing a plurality of tire monitors, each monitor for mounting in one of the plurality of tires, each monitor comprising means for determining tire pressure and a transmitter for transmitting a signal representative of the tire pressure determined. The method further comprises providing a receiver for mounting on board the vehicle for receiving the tire pressure signals, the receiver comprising an antenna to be located on the vehicle at a site, wherein each tire pressure signal has an amplitude and, for each tire location, the amplitude has a unique pattern over time for the antenna site. The method still further comprises providing a controller for mounting on board the vehicle, the controller to be provided in communication with the receiver for collecting and processing the tire pressure signals to automatically identify the tire locations associated therewith based on the unique amplitude patterns, the controller further for generating control signals for use in conveying tire pressure and location information to a vehicle occupant.
These and other features and advantages of the present invention will be readily apparent upon consideration of the following detailed description of the invention in conjunction with the accompanying drawings.